1. Field of the Invention
The present invention relates to a ring gauge for checking external diametral dimensions of parts having a surface of rotation, comprising support means; two feelers movable with respect to the support means, the feelers being adapted to touch the part to be checked; two arc-shaped arms coupled to said support means and adapted to support said feelers; and transducer means adapted to provide an electric signal depending on the position of the feelers.
2. Description of the Prior Art
Known ring gauges for checking external diameters comprise a support structure and a ring coupled to the support structure through a flat spring. Fixed to the ring and passing through a hole of it is a cartridge gauging head having a movable feeler protruding internally with respect to the ring. A carbide reference contact or fixed feeler adapted to touch the surface of the part to be checked is fixed to the internal surface of the ring, at a position diametrically opposite that where the movable feeler is arranged. The flat spring permits centering of the ring with respect to the part. Other known ring gauges have a substantially U-shaped arm-set, housed within an annular casing and fixed to the casing so as to perform angular displacements about a point of the casing, for permitting centering of the arm-set with respect to the part. Fixed at the ends of the U and protruding internally with respect to the casing are, respectively, a cartridge type gauging head and a carbide reference contact. These known ring gauges are rather expensive and have large overall dimensions, mainly due to the use of cartridge gauging heads, which moreover may cause incorrect operation due to possible seizures. For zero setting these ring gauges it is necessary to act on the cartridge heads and therefore it is necessary to have skilled operators which have to reach components of the ring gauge not immediately accessible.